Dilator naris anterior

The dilator naris anterior is a muscle of the nose that encircles the nostril and participates in widening it. Sometimes the dilator naris anterior along with the dilator naris posterior are referred to as parts of the nasalis muscle. The dilator naris anterior widens the nostrils and together with the alar part of the nasalis may also function to prevent collapse of the nasal valve during inspiration.

Check it out